A couple of things for when you play Senna, because these 2 things you didn't notice, at least as far as I've watched, and are pretty essential. Your Q is a _targeted_ ability. That's why it felt weird to you. You can cast it on a minion in front of an enemy, for example. -Ah, I just noticed they've told you this in chat.- Your Ult is _global._ You can kill enemies and shield allies from all the way across the map, helping in teamfights even when you're not around. In general you don't want to attack minions when you're playing support. You can execute minions with the support item (preferably melee minions and cannons since you share the gold and those are worth most), but in general I'd leave the minion wave alone. If you push the wave, the fighting between you and your enemies happens on _their_ side of the lane, while you often want to fight on _your_ side of the lane. In general, I'd say Senna is not a great support for a new player. There are supports that are way more effective at low-level play, like Morgana, or Lux, or tanky supports like Braum or Nautilus.
A couple of things for when you play Senna, because these 2 things you didn't notice, at least as far as I've watched, and are pretty essential.
Your Q is a _targeted_ ability. That's why it felt weird to you. You can cast it on a minion in front of an enemy, for example. -Ah, I just noticed they've told you this in chat.-
Your Ult is _global._ You can kill enemies and shield allies from all the way across the map, helping in teamfights even when you're not around.
In general you don't want to attack minions when you're playing support. You can execute minions with the support item (preferably melee minions and cannons since you share the gold and those are worth most), but in general I'd leave the minion wave alone. If you push the wave, the fighting between you and your enemies happens on _their_ side of the lane, while you often want to fight on _your_ side of the lane.
In general, I'd say Senna is not a great support for a new player. There are supports that are way more effective at low-level play, like Morgana, or Lux, or tanky supports like Braum or Nautilus.